On Issue 2 boards these are underneath the heatsink, on issue 3 and up they are immediately northeast of the speaker. Now locate the ROM links on the PCB (marked H-N). Also shown is the ground point required for the modification, higlighted in yellow. I find applying a little hot air after the solder has been removed from all the pins makes this process much easier and less risky. Take your time during this step and dont apply excessive force to the IC to remove it, even when all pins look to be free. Then you’ll need to desolder the orignal ROM and replace it with a socket. Take care to ensure the socket notch is correctly oriented.įirstly, disassemble the machine and remove the heatsink. Preparing the PCB Spectrum ROM removed and socket installed. If you’re interested in the technical details of this modification, skip to the end – the rest of the article deals purely with performing the modification itself. 27C256 EPROM (and a means to program it).If the ROM in your 48K Spectrum has failed, or you simply want to try an alternative ROM image, then you’ll need to make some minor modifications to your machine in order for it to take an EPROM, since the Spectrum ROM pinout (a 23128 device) doesn’t exactly match that of the most readily available replacement, the 27C256 EPROM. Pinouts of the 23128 PROM and 27C256 EPROM, respectively. Share the post "Fitting an EPROM to a 48K Spectrum"
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